A numerical technique for modeling fatigue crack propagation of multiple coplanar cracks is presented. The proposed method couples the extended finite element method (X-FEM) [Int. J. Numer. Meth. Engng. 48 (11) (2000) 1549] to the fast marching method (FMM) [Level Set Methods & Fast Marching Methods: Evolving Interfaces in Computational Geometry, Fluid Mechanics, Computer Vision, and Materials ...

Purpose – The purpose of this work is to describe the effects of the length of cracks and the patch size on the stress intensity factors in a bonded composite repair structure containing multiple site damage. Design/methodology/approach – Finite element method was applied to simulate a bonded repair of a cracked aluminum plate with multiple site damage. A two-dimensional three-layer technique w...

In this project, investigation of stress concentration factor is carried out. Some specimens with edge notches, multiple edge notches, and holes are fabricated. While two specimens are hand sawed to produce edge cracks. The stress concentration factor (K) value is compared between the theoretical values found in standard K value chart with our experimental results. Effect of multiple notches is...

The extended and generalized finite element methods are reviewed with an emphasis on their applications to problems in material science: (1) fracture, (2) dislocations, (3) grain boundaries and (4) phases interfaces. These methods facilitate the modeling of complicated geometries and the evolution of such geometries, particularly when combined with level set methods, as for example in the simul...

This paper develops the extended finite element method (XFEM) to evolve patterns of multiple cracks, in a brittle thin film bonded to an elastic substrate, with a relatively coarse mesh, and without remeshing during evolution. A shear lag model describes the deformation in three dimensions with approximate field equations in two-dimensions. The film is susceptible to subcritical cracking, obeyi...

MRS BULLETIN • VOLUME 31 • MARCH 2006 167 From Mirror to Mist: Cracking the Secret of Fracture Instabilities When cracks in a material propagate, bonds between atoms are broken, generating two new surfaces. Experiments have shown that cracks moving at low speeds create atomically flat, mirror-like surfaces, whereas cracks moving at higher speeds create increasingly rough fracture surfaces. Dyna...

We review recent theoretical progress on the dynamics of brittle crack fronts and its relationship to the roughness of fracture surfaces. We discuss the possibility that the intermediate scale roughness of cracks, which is characterized by a roughness exponent approximately equal to 0.5, could be caused by the generation, during local instabilities by depinning, of diffusively broadened corruga...

a two-dimensional single particle finite element model was used to examine the effects of particle fragmental pattern on the average molecular weights, polymerization rate and particle overheating in heterogeneous ziegler-natta olefin polymerization. a two-site catalyst kinetic mechanism was employed together with a dynamic two-dimensional molecular species in diffusion-reaction equation. the i...

Figure 1 Upper two pictures and lower left picture: multiple urothelial cracks seen after hydrodistension, lower right picture: glomerulation (petechiae).

MAX phase materials are emerging as attractive engineering materials in applications where the material is exposed to severe thermal and mechanical conditions in an oxidative environment. The Ti2AlC MAX phase possesses attractive thermomechanical properties even beyond a temperature of 1000 K. An attractive feature of this material is its capacity for the autonomous healing of cracks when opera...